1. Field of the Invention
This invention relates to analyte enclosures to be used in conjunction with sensing devices. In particular, this invention relates to evaluation of the contents of a sealed primary container by means of an integral sensor which is separated from the contents of the sealed primary container yet provides information on quality of the contents of the primary container without breaking the sealed system.
2. Description of the Related Art
The background for this invention is presented in the context of human blood cells, because of their great societal importance and especially because of limitations of current procedures used for their storage. However, the invention could have been presented in a context of food storage and processing, production of valuable molecules by biofermentation, or industrial processing such as electroplating or acid/base treatment of products.
Typically, blood is obtained from donors and fractionated into components including erythrocytes, platelets, lymphocytes, and plasma. Erythrocytes and platelets are separately packaged as “units”, which then are held at appropriate temperature and distributed for later transfusion into patients. Each unit is aseptically placed into a previously sterilized plastic bag and sealed therein. Despite careful attention to aseptic processing, there is a probability that a given unit of blood cells will be contaminated with microbes.
With erythrocytes, current FDA regulations limit use to within 24 days after collection in an effort to minimize risk to patients from infusion of a contaminated unit of cells. Often endotoxins rather than the bacteria per se cause the problem with erythrocytes. With platelets, there is similar concern about microbial contamination, but their use is limited to 5 days because of metabolic self-damage. A recent review (Blajchmann, 1999) noted that 1 in ˜2,500 units of platelets and 1 in ˜38,500 units of erythrocytes was contaminated with bacteria. A New Zealand study reported that 1 of 65,000 individuals will get very sick after transfusion of erythrocytes and 1 of 104,000 will die because of one specific organism. Data from other countries, including the USA, provide both higher and lower risk factors, but there is substantial hazard associated with use of erythrocytes and especially platelets (Lee, 1999).
Currently there is no acceptable method to determine if a unit of blood is contaminated just before transfusion of the contents into a patient. This is because sampling the contents requires opening the bag, with resultant risk of introducing contamination, and evaluation of the sample acquired. Because a laboratory setting is required, it is difficult or impossible to make a “use” or “non-use” decision in a few minutes. Clearly, a diagnostic method or device to allow a use or non-use decision without opening the unit of blood would have great utility if it had a very high probability of giving the correct conclusion.